long gun vs machine gun

long gun

noun
  • A firearm, such as a shotgun or rifle, which is fired while braced against the shoulder. 

machine gun

noun
  • A type of fully automatic firearm that fires bullets in rapid succession by a single action of the trigger and is capable of sustained fire. 

How often have the words long gun and machine gun occurred in a corpus of books? (source: Google Ngram Viewer )